201120251 六、發明說明： 相關申請案之參照 本申請案係根據於2009年12月4日提出申請之日本 國特許出願第2 009-2<76 649號主張優先權，該全體揭示內 容係根據參照而援引至本說明書中^ 【發明所屬之技術領域】 本發明係關於多孔質金屬箔及其製造方法。 【先前技術】 近年來，作爲行動電話及筆記型電腦等之可攜式電子 機器、電動車、及油電混合車用的蓄電裝置，鋰離子蓄電 池與鋰離子電容器乃受到矚目。此般蓄電裝置的負極集電 體’係使用多孔質金屬箔或正探討其使用。此係藉由構成 爲多孔質，而具有可減輕重量（藉此可改善汽車的燃料費 用）’能夠以活用孔之定錨效果來提升活性物質的密著力 ，以及可利用孔來有效率地進行鋰離子的預摻雜（例如垂 直預摻雜）等優點之故。 此般多孔質金屬箔之一般所知的製造方法，可列舉出 (1 )預先藉由絕緣性覆膜將基材表面遮蔽爲期望的圖型 ，然後從該上方施以電解電鑛而將孔形成如圖型之方法， (2)預先將特有的表面粗糙度或表面性狀賦予至基材表 面，然後從該上方施以電解電鍍來控制核生成之方法，（ 3)藉由蝕刻或機械加工將無孔質的金屬箔進行穿孔之方 -5- 201120251 法，（4)藉由對發泡金屬或不織布進行電鍍之手法來形 成三維網目結構之方法等。 尤其關於上述（2)的方法，由於步驟相對簡便且適 合於量產，所以係提出各種技術。例如專利文獻1中，係 揭示一種藉由對表面粗糙度Rz爲0.8/zm以下之陰極施以 電解電鍍，而製造出細微開孔之金屬箔之方法。專利文獻 2中，係揭示一種藉由陽極氧化法將氧化覆膜形成於由鈦 或鈦合金所構成之陰極體的表面，並將銅電析於陰極體的 表面以形成多孔質銅箔，並從陰極體中剝離之方法。專利 文獻3中，係揭示一種爲了製造出附有鋁合金載體之開孔 金屬箔，係藉由將鋁蝕刻以形成均一的突出部，以該突出 部作爲電析的核，並逐漸使金屬粒子成長而連結之方法。 然而，藉由此等技術所得之多孔質金屬箔，實際上由 於有作爲箔的強度低之疑慮，所以無法獲得充分高的開孔 率。此外，長條狀的製造較爲困難，在陽極氧化法中連續 地剝離時’氧化覆膜會被破壞，多孔質膜的剝離性與開孔 率的安定性上存在著課題。尤其在鋰離子蓄電池、鋰離子 電容器等之蓄電裝置的負極集電體中，伴隨著高性能化， 係要求更高的開孔率。 先前技術文獻 專利文獻 專利文獻1 :日本特開平1 0- 1 95689號公報 專利文獻2:日本特許第3262558號公報 201120251 專利文獻3:日本特開2005-251429號公報 【發明內容】 本發明者們，此次係發現到藉由在形成有龜裂的某種 剝離層上進行金屬電鏟，能夠以高生產性且低成本來製得 具有較佳特性之多孔質金屬箔。 因此，本發明之目的係在於以高生產性且低成本來製 得具有較佳特性之多孔質金屬箔者。 亦即，根據本發明，係提供一種由以金屬纖維所構成 之二維網目結構所形成的多孔質金屬箔。 此外，根據本發明，亦提供一種多孔質金屬箔製品， 其係具備：導電性基材、設置在前述導電性基材上之剝離 層、以及設置在前述剝離層上之多孔質金屬箔而成；前述 剝離層係可使前述多孔質金屬箔從前述剝離層中剝離者。 再者，根據本發明，亦提供一種多孔質金屬箔的製造 方法，其係含有：將剝離層形成於導電性基材，此時使前 述剝離層上產生龜裂，將可優先析出於前述龜裂之金屬電 鍍於前述剝離層，沿著前述龜裂使無數個金屬粒子成長， 藉此形成由以金屬纖維所構成之二維網目結構所形成的多 孔質金屬箔之步驟。 【實施方式】 多孔質金屬箔 第1圖爲本發明之多孔質金屬箔的一例之上方模式圖 201120251 。如第1圖所示，本發明之多孔質金屬箔1 〇 ’係由以金 屬纖維11所構成之二維網目結構所形成。此多孔質金屬 箔10，較佳爲具有3〜80%，尤佳爲具有5~60% ’更佳爲 具有10~55%，特佳爲具有20〜55%之開孔率。在此，開 孔率P(%)，係使用多孔質金屬箔的重量Wp相對於具 有與多孔質金屬箔爲同等的組成及尺寸之無孔質金屬箔的 理論重量Wn所佔之比率Wp/Wn，其藉由P = l〇〇-[( Wp/Wn) xlOO]所定義。此理論重量Wn的算出，係測定 出所得之多孔質金屬箔的尺寸，從所測得之尺寸中算出體 積（亦即理論之無孔質金屬箔的體積），並將所製作之多 孔質金屬箔之材質的密度乘上所得之體積而藉此進行。 如此，本發明之多孔質金屬箔〗〇，即使提高開孔率 ，亦可藉由遍佈爲二維網目狀之無數條金屬纖維11顯現 出高強度。因此，可在不需擔心強度降低，將開孔率提高 至以往所未達到之水準。例如，多孔質金屬箔1 〇，可將 藉由後述測定方法所測得之拉伸強度，較佳地構成爲 10N/10mm以上，更佳地構成爲15N/I0mm以上，藉此可 有效地防止多孔質金屬箔的斷裂。尤其在將載體附著於多 孔質金屬箔之狀態下處理時，即使是較上述範圍更低的拉 伸強度，亦無問題。此時可在不需擔心拉伸強度下，將開 孔率提高至極限。 多孔質金屬箔，較佳係具有3~40 # m的厚度，尤佳 爲3〜30ym，更佳爲5〜25/zm，特佳爲1〇~20私m，最佳 爲10〜15/zm。位於此範圍內時，高開孔率與高強度之均 -8 - 201120251 衡性佳。本發明之多孔質金屬箔，由於是由以金屬纖維所 構成之二維網目結構所形成，所以多孔質金屬箔的厚度相 當於金屬纖維的最大剖面高度。此厚度，較佳係藉由使用 有較多孔質金屬箔的孔尺寸更大之測定件之市售的膜厚測 定裝置來測定。 金屬纖維π是金屬製的纖維，所使用之金屬可因應 用途來適當地決定，並無特別限定。較佳的金屬係含有選 自由銅、鋁、金、銀、鎳、鈷、及錫所成之群組的至少一 種而成。在此所謂的「含有~而成」，係意味著只要是含 有上述列舉的金屬元素爲主之金屬或合金即可，且容許可 含有其他金屬元素或不可避免的雜質作爲剩餘部分者，尤 佳爲金屬及合金的50重量％以上是由上述列舉的金屬元 素所構成者，典型例子可列舉出由上述列舉的金屬元素及 不可避免的雜質所構成者。此等定義亦同樣可適用在對於 下列金屬所敘述的相同表現。此等金屬中，適用於鋰離子 蓄電池、鋰離子電容器等之蓄電裝置的負極集電體者，係 含有選自由銅、銅合金、鎳、鈷、及錫所成之群組的至少 一種而成，尤佳爲銅。尤其是，二維網目結構較佳係具有 起因於基材表面上所形成之龜裂的不規則形狀而成。 金屬纖維11的線徑較佳爲5〜80 m，尤佳爲5〜50 ym’更佳爲8〜30/zm，最佳爲10~20;/m。「線徑」係定 義爲從正上方觀看多孔質金屬箔時之纖維11的寬度（粗 度），可使用場輻射型掃描電子顯微鏡（FE-SEM)、掃 描離子顯微鏡（S IM )等來測定。位於此範圍時，高開孔 -9 - 201120251 率與高強度的均衡性佳。 根據本發明之較佳型態，如$ 1圖所示，金屬 11爲分枝狀纖維，且分枝狀纖維係不規則地遍佈而 多孔質金屬箔。纖維11，係起因於沿著後述剝離層 裂之核生成，使無數個金屬粒子被連結而藉此形成， 構成金屬纖維，較佳是藉由粒子成長使鄰接之金屬粒 此緊密結合，所以構成金屬纖維之金屬粒子，亦可不 完全的粒子形狀。此外，如第2圖所示，構成金屬 11之金屬粒子，典型爲具備具有球狀部11a與底部 之半球狀的形態，全部之金屬粒子的底部lib位於同 底面上，全部之金屬_粒子的球狀部11a以基底面爲基 於相同側。此時，沿著基底面之底部1 1 b的寬度D 線徑，球狀部1 1 a的最大剖面高度Η相當於多孔質金 的厚度。此基底面以及位於其上方之底部lib，係反 製造時所用之剝離層的平面形狀，當藉由其他製法來 時，並不限定於此形狀。根據本發明者們的經驗， 1 1中，最大剖面高度Η相對於線徑D之平均比率並 別限定，典型爲0.30〜0.70，尤其典型爲0.40~0.60, 型爲0.45〜0.55，最典型爲0.50，此平均比率可藉由 地改變電鍍條件等來調整。此外，根據本發明者們的 ’多孔質金屬箔10之孔的平均面積並無特別限定’ 爲3~5000以！112，尤其典型爲3〜3 000/^1112，更典 3〜2〇〇〇 y m2。再者，根據本發明者們的經驗，多孔質 箔10中，具有最大的孔的面積之1/2以下的面積（ 纖維 構成 的龜 爲了 子彼 具有 纖維 lib 一基 準位 成爲 屬箔 映出 製造 纖維 無特 更典 適當 經驗 典型 型爲 金屬 亦即 -10- 201120251 約23 5 0 v m2以下）之孔的個數相對於孔的全體個數所佔 之比率，並無特別限定，典型爲6〇%以上，尤其典型爲 70%以上，更典型爲80%以上。 製造方法 以下係說明本發明之多孔質金屬箔的製造方法的一例 ’但本發明之多孔質金屬箔並不限定於此製造方法，亦包 含藉由不同製造方法所製造者。 第3圖係顯示本發明之多孔質金屬箔的製造步驟的流 程。本發明之製造方法，首先準備導電性基材12作爲用 以製造多孔質金屬箔之支撐體。導電性基材，只要是具有 可經電鍍之程度的導電性之基材者即可，可使用無機材料 、有機材料、層合體、以及以金屬構成表面之材料的任一 者，較佳爲金屬。此般金屬的較佳例子，可列舉出銅、鎳 、鈷、鐵、鉻、錫 '鋅、銦、銀、金、鋁、及鈦等金屬， 以及含有此等金屬元素的至少一種之合金，尤佳爲銅、銅 合金、鎳、鎳合金、鈦、鈦合金，以及不銹鋼。導電性基 材的形態並無限定，可使用箔、板、轉筒等之各種形態的 基材。爲轉筒時，.可將導電性金屬板捲繞於轉筒本體來使 用’此時之導電性金屬板的厚度較佳爲1〜20mm。導電性 基材’係預先在加工中或是使用不久前預先支撐所製造出 之多孔質金屬箔，以提升多孔質金屬箔的處理性。尤其將 金屬箔用作爲導電性基材者，乃具有在多孔質金屬箔的製 造後，可直接將作爲導電性基材的金屬箔予以再利用，或 -11 - 201120251 是經溶解及製箔後予以回收之優點，故較佳。此時，將金 屬箔的厚度構成爲10// m〜1 mm者，可確保在金屬箔的製 造步驟及之後的加工·運送步驟中不會產生皺折之強度， 故較佳。 因導電性基材的材質或粗糙度之不同，使剝離層之龜 裂的形狀有所不同，故多孔質金屬箔的開孔率等特性可能 產生變化。另一方面，因金屬電鍍的種類或電鍍條件之不 同，多孔質金屬箔的形狀亦可能產生變化》因此，只須以 考量此等情形來獲得期望的多孔質金屬箔之方式，因應必 要來適當地進行導電性基材的選擇、剝離層的形成條件及 /或電鏟條件的設定即可。 然後在導電性基材1 2上形成剝離層1 3，此時係在剝 離層13上使龜裂13a產生。較佳係在剝離層13的形成之 前，對導電性基材12預先施以酸洗淨、脫脂等之前處理 來清潔該表面者。剝離層13，爲用以使形成於其上之多 孔質金屬箔10的剝離變得容易之層，所以使用具有可產 生龜裂13a，在龜裂13a容易被電鍍且在無龜裂部分13b 不易被電鍍之性質的材料。亦即，係使用可藉由電鍍優先 地析出某種金屬於所產生之龜裂13a上的材料作爲剝離層 13。此外，此剝離層可形成爲多層，此時，可爲僅於上層 形成有龜裂者，或是不僅於上層，於其下方之層亦形成有 龜裂者。此外，於剝離層的表面亦可存在有類鑽碳（DLC )等。龜裂1 3 a，較佳係控制爲藉由剝離層1 3的應力而 自然地產生者，亦可不需與成膜同時形成，而是在之後的 -12- 201120251 洗淨及乾燥步驟、機械加工等當中所產 不希望產生者，但在本發明之製造方法 活用此龜裂者爲特徵。尤其是，龜裂一 規則地遍佈成二維網目狀所形成之特性 此龜裂來形成金屬纖維，可製得高開孔 質金屬箔。關於龜裂，在一般的成膜程 生，所以該產生條件對從事成膜之業者 知者，可在其經驗及知識的範圍內容易 藉由縝密規劃電鍍浴等的組成控制、剝 密度的條件、浴溫、攪拌條件、後熱處 剝離層1 3，較佳係含有選自由鉻 、及鎢所成之群組的至少一種而成，或 樹脂類）所構成，就連續剝離性、耐久 點來看，尤佳係含有選自由硬度高之鉻 群組的至少一種而成，就容易藉由惰態 點來看，更佳係由鉻、鉻合金或鉻氧化 層13的厚度，較佳爲lnm~100//m，尤 更佳爲1〜30/zm，最佳爲2~15/zm。藉 及厚度，可產生龜裂，且同時可使剝離 材成爲高電阻而使形成於層上之多孔質 膜及剝離。因此，剝離層較佳是選.擇較 電阻之材料。 剝離層1 3的形成方法並無特別限 鍍、無電解電鍍、濺鍍法、物理氣相沉 生者。龜裂一般是 中，反而是以積極 般具有分枝的線不 ，因此，藉由沿著 率及高強度之多孔 序中經常擔心其產 而言爲經驗上所熟 地選擇。例如，可 離層的厚度、電流 理等來進行》 、鈦、組、鈮、鎳 是由有機物（例如 性及耐腐蝕性之觀 、鈦、及鎳所成之 的形成來剝離之觀 物所構成者。剝離 _佳爲 〇.l~50"m， 由構成此般的組成 層相對於導電性基 金屬箔1 〇容易成 導電性基材爲更高 定，可採用電解電 積法（PCD)、化 -13- 201120251 學氣相沉積法（CVD )、溶膠凝膠法、粒子蒸鍍法等之種 種成膜方法。就製造效率等觀點來看，剝離層13較佳亦 藉由電解電鍍所形成。剝離層13上，在不脫離本發明之 主旨的範圍內，可因應必要更施以熱處理及/或硏磨。亦 即，硏磨可容許洗淨表面之程度，但當然不可過度進行至 使龜裂消失。如此所得之剝離層13上，較佳係藉由水等 來進行洗淨並進行乾燥。 進行電解鍍鉻時，較佳的鍍鉻液，可列舉出薩金特（ Sargent )浴及硬質鍍鉻浴，尤佳爲硬質鍍鉻浴。市售之 硬質鍍鉻浴的例子，可列舉出Meltex公司製的 Anchor-1127、 Atotech 公 司製的 HEEF-25、 及 MacDermi 公司製 的Mac . 1。此等鍍鉻液的浴組成及電鍍條件如下所述， 但只要可獲得期望的多孔質金屬箔者’亦可脫離以下所示 之範圍。 -14 - 201120251 [第1表] 第1表：較佳之鍍鉻液的組成及電鍍條件 基本浴 ίϊ售的硬質鍍鉻浴 薩金特浴 Anchor-1127 HEEF-25 Mac · 1 浴組成(g/L) 鉻酸酐 250 280-320 200-300 250-300 硫酸 2.5 3.3 〜3.9 (l.l~1.3wt%) 2.0-4.5 3.5-4.0 電鍍條件 陰極電流密度 (A/dm2) 20-40 30-60 20-90 10-100 溫度（。〇 45-60 55-60 50-65 55-60 安定的鍍鉻浴，典型爲存在有少量3價鉻，該量約爲 2〜6g/L。此外，亦可將有機磺酸等觸媒添加於硬質鍍鉻浴 。鉻酸酐的濃度，可藉由波美度來管理。再者，由於鐵、 銅、氯化物離子等雜質會對電鍍狀態造成影響，所以必須 注意雜質之溶解量的上限管理。鑛鉻中所用之陽極，較佳 可使用將氧化鉛或Pb-Sn合金塗膜於鈦者，此般陽極的代 表性市售品，可列舉出SPF公司的Ti-Pb電極（Sn: 5% )及 Japan Carlit 公司製的 Exceload LD。 接著’將可優先析出於龜裂13a之金屬電鍍於剝離層 13，沿著龜裂13a使無數個金屬粒子11成長，藉此形成 由以金屬纖維所構成之二維網目結構所形成的多孔質金屬 箱10。如前述般，剝離層13係具備：具有容易被電鍍之 龜裂13a，以及具有不易被電鍍之無龜裂的表面部分m 。在龜裂13a容易被電鍍者，是由於具有龜裂13a之部分 -15- 201120251 者，電流較無龜裂部分13b更易流通，所以核生成及其成 長在龜裂13a優先地產生之故。可優先析出於龜裂13a之 金屬，較佳係含有選自由銅、鋁、金、銀、鎳'鈷'及錫 所成之群組的至少一種而成，尤佳係含有選自由銅、銀及 金所成之群組的至少一種而成，更加爲銅。 多孔質金屬箔1 〇的形成方法並無特別限定，可列舉 出電解電鍍、無電解電鍍，由於電解電鍍可有效率地將金 屬析出於龜裂1 3 a，故較佳。電鍍的條件，可依循一般所 知的方法來進行，並無特別限定。例如當進行鍍銅時，較 佳係藉由鑛硫酸銅浴來進行。當進行鍍銅時，電鍍浴的組 成及電鍍條件，爲硫酸銅五水合物濃度：120~3 50 g/L、 硫酸濃度：50〜200g/L、陰極電流密度：l〇~80A/dm2、浴 溫：40~60°C，但並不限定於此。 電鍍液，可適當地加入添加劑以提升金屬箔的特性。 例如爲銅箔時，此般添加劑的較佳例子，可列舉出膠、明 膠、氯、硫脲等之含硫化合物、聚乙二醇等之合成系添加 劑。藉此使用此等較佳的添加劑，可控制金屬箔的力學特 性及表面狀態。添加劑的濃度並無特別限定，一般爲 1 〜3 OOppm 〇 最後’將多孔質金屬箔從具有剝離層之導電性基材中 剝離，而得單體的多孔質金屬箔。剝離後，可轉印至附有 黏著劑的薄膜等之其他基材。惟此剝離步驟並非必要，可 構成惟在介於剝離層而附有基材之狀態下直接當作多孔質 金屬箔製品，並且於使用時再剝離，此時，不僅多孔質金 -16 - 201120251 屬箔的處理性提升，且由於以基材所支撐而不要求如此高 的強度’所以亦可構成極高開孔率或極薄膜厚。 用途 本發明之多孔質金屬箔的代表性用途，可列舉出鋰離 子蓄電池與鋰離子電容器等之蓄電裝置的負極集電體，除 此之外’亦可使用於微粉分級用或固液分離處理用的網版 裝置、觸媒的撐體、使用在微生物之保管用容器的氧供應 口之網、無塵室用防塵過濾器、液體改質用過濾器、電磁 波屏蔽、磁性用材料、導電用材料、裝飾薄片等之各種用 途。例如，藉由將多孔質金屬箔作爲導電用材料等使用在 印刷電路基板的內層，可從孔當中，使來自樹脂或溶劑等 之氣體散逸出，藉此可抑制氣泡（膨脹）的產生。此外， 藉由將多孔質金屬箱作爲導電用材料等使用在電路的形成 ’可達到因金屬用量的降低所達成之輕量化。 實施例 藉由下列實施例，更具體地說明本發明。 例A 1 :多孔質金屬箔的製作 準備厚度3 5 /z m的銅箔作爲導電性基材。並以下列 步驟對此銅箔施以鍍鉻作爲剝離層。首先在4〇 <^下，將銅 箱浸漬於添加水並調整爲1 20mL/L之印刷配線基板用酸 性清潔液（Murata公司製’ pAC_2〇〇 ) 2分鐘。將經如此 -17- 201120251 洗淨的銅箔，在室溫下浸漬於50mL/L的硫酸1分鐘來進 行酸活化。將經酸活化後的銅箔，浸漬於溶解有18 Og/L 的Econochrome 300 ( Meltex公司製）及 lg/L的精製濃 硫酸之鍍鉻浴，在溫度：45eC、電流密度：20A/dm2的條 件下進行15分鐘的鍍鉻。將形成有鍍鉻層之銅箔進行水 洗及乾燥。以XRF (螢光X射線分析）來測定所得之鍍 鉻層的厚度，約爲2#m，於鍍鉻層的表面，可確認到被 視爲因電鍍應力所產生之無數個龜裂。 於產生此龜裂之鍍鉻層上施以鍍硫酸銅。此鍍硫酸銅 ，係將施以鍍鉻後的銅箔，浸漬於溶解有25 Og/L的硫酸 銅五水合物（銅濃度約64g/L)及硫酸80g/L之鍍硫酸銅 浴’並在電流密度：20A/dm2、電鍍時間：150秒、陽極 :D S E (氧產生用不溶性電極）、浴溫：4 0 °C的條件下進 行。此時，與鍍鉻層的最表面相比，電流在龜裂的部分上 更容易流通，所以銅的粒子係以龜裂爲起點來成長。其結 果可在鍍鉻層上形成有由銅纖維所構成之二維網目結構作 爲多孔質金屬箔。最後，將多孔質金屬箔從鍍鉻層中物理 性地剝離，而獲得分離的多孔質金屬箔。 例A2 :多孔質金屬箔的觀察 藉由場輻射型掃描電子顯微鏡（FE-SEM)，從各種 角度來觀察例A1中所得之多孔質金屬箔。首先從正上方 (傾斜角〇度）及斜向上方（傾斜角4 5度）觀察多孔質 金屬箔之未與剝離層接觸的面（以下稱爲成長面），分別 -18- 201120251 獲得如第4圖及第5圖所示之圖像。此外，翻轉多孔質金 屬箔’從正上方（傾斜角〇度）及斜向上方（傾斜角45 度）觀察多孔質金屬箔之與剝離層接觸的面（以下稱爲剝 離面），分別獲得如第6圖及第7圖所示之圖像。從此等 圖中可得知，成長面上可觀察到起因於金屬粒子的球狀部 之佛珠狀的凹凸，相對於此，剝離面可觀察到起因於金屬 粒子的底部之平面及沿著龜裂所形成之中心線。 再者，使用集束離子束加工裝置（FIB )加工多孔質 金屬箔之金屬纖維的剖面後，使用掃描離子顯微鏡（SIM )來觀察，可獲得如第8圖所示之圖像。如該圖所示，可 觀察到金屬纖維的剖面組織係以龜裂爲起點呈輻射狀析出 ，金屬纖維的剖面形狀爲含有球狀部與平面狀底面之半月 狀。從此等圖所示之尺規來算出金屬纖維的線徑（粗度） 時，爲30ym。計算出金屬纖維剖面之最大剖面高度Η相 對於線徑D的比率時，約爲0.5 0。此外，每單位面積之 孔的個數約爲3 00個/mm2。此外，觀察到之最大的孔的面 積約爲4700 μ m2，具有最大的孔的面積之1/2以下的面 積（亦即約2 3 5 0 y m2以下）之孔的個數相對於孔的全體 個數所佔之比率，約爲90%。 例A3 :開孔率的測定 藉由重量法，以下列方式測定出例A1中所得之多孔 質金屬箔的開孔率。首先’藉由數位測長機（Digimicro ΜΗ-1 5M，Nikon公司製）測定多孔質金屬箔的膜厚，爲 -19- 201120251 14.7;zm。此時，測定支架係使用MS-5C( Nikon公司製 )，測定件使用D i g i m i c r ο Μ Η -1 5 Μ的標準裝備測定件° 此外*測定lOOmmxlOOmm平方的單位重量’爲〇.94g° 另一方面，以銅的密度爲8.92g/cm3來計算，求取膜厚 14,7vm、lOOmmxlOOmm平方之無孔質銅箔的理論重量’ 爲1 .3 1 g。使用此等値，以下列方式來計算多孔質金屬箔 的開孔率，而算出2 8 %之値。 (開孔率）= 100-[(樣本的單位重量）/(無孔質銅箔的理論 重量）]xl〇〇 = 100-[(0.94)/(1.31)]xl00 = 28% 例A4 :拉伸強度的測定 藉由依據 JIS C6511之方法，以下列方式測定出例 A1中所得之多孔質金屬箔的拉伸強度。首先，從多孔質 金屬筢中裁切出lOmmxlOmm的試驗片。如第9圖所示， 以隔著50mm的間隔，將此試驗片20的兩端夾持在拉伸 強度測定機（Autograph，島津製作所公司製）的上下兩 個固定夾具21、21並予以固定後，以50mm/分的拉伸速 度進行拉伸，藉此測定出拉伸強度。此時，拉伸強度測定 機中，係使用1 kN的測力器。其結果係拉伸強度爲 15N/10mm寬。此外，此時之試驗片的伸長率爲 0.8%。 從該結果中，可考量本發明之多孔質金屬箔乃具有可承受 -20- 201120251 實用性要求之強度。 例B 1 :多孔質金屬箔的製作 準備由SUS304所構成之不銹鋼板作爲導電性基材》 並以下列步驟對此不銹鋼箔施以2^m的鍍鉻作爲剝離層 。首先在 40°C下，將不銹鋼板浸漬於添加水並調整爲 l2〇mL/L之印刷配線基板用酸性清潔液（Murata公司製， PAC-2 00 ) 2分鐘。將經如此洗淨的不銹鋼板，在室溫下 浸漬於50mL/L的硫酸1分鐘來進行酸活化。將經酸活化 後的不銹鋼板，浸漬於市售的硬質鍍鉻浴（HEEF-25， Atotech公司製），在陰極電流密度：20A/dm2、電解時間 :400秒、浴溫：45°C、庫侖量.：8000C/dm2、電極面積 :1.2dm2、極間距離：90mm、的條件下進行鍍鉻。將形 成有鑛鉻層之不銹鋼板進行水洗及乾燥。以XRF (螢光X 射線分析）來測定所得之鍍鉻層的厚度，約爲2 // m，於 鍍鉻層的表面，可確認到被視爲因電鍍應力所產生之無數 個龜裂。 於產生此龜裂之鍍鉻層上施以鍍銀。此鍍銀，係將施 以鍍鉻後的不銹鋼板，浸漬於溶解有氰化鉀25g/L、氰化 銀（Ag爲 50g/L )及磷酸鹽等之市售的鑛銀浴（ Selenabright C，日本高純度化學公司製），並在陰極電 流密度：l.〇A/dm2、電解時間：469秒間、浴溫：40°C的 條件下進行。此時，與鍍鉻層的最表面相比，電流在龜裂 的部分上更容易流通，所以銀的粒子係以龜裂爲起點來成 S- -21 - 201120251 長。其結果可在鍍鉻層上形成有由銀纖維所構成之二維網 目結構作爲多孔質金屬箔。最後，將多孔質金屬箔從鍍鉻 層中物理性地剝離，而獲得分離的多孔質金屬箔。 例B2 :多孔質金屬箔的觀察 藉由場輻射型掃描電子顯微鏡（FE-SEM )，從各種 角度來觀察例B1中所得之多孔質金屬箔。首先從正上方 (傾斜角〇度）觀察多孔質金屬箔之未與剝離層接觸的面 (以下稱爲成長面），獲得如第10圖所示之圖像。此外 ，翻轉多孔質金屬箔，從正上方（傾斜角0度）觀察多孔 質金屬箔之與剝離層接觸的面（以下稱爲剝離面），獲得 如第11圖所示之圖像。從此等圖中可得知，成長面上可 觀察到起因於金屬粒子的球狀部之佛珠狀的凹凸，相對於 此，剝離面可觀察到起因於金屬粒子的底部之平面及沿著 龜裂所形成之中心線。從此等圖所示之尺規來算出金屬纖 維的線徑（粗度）時’爲1 1 μ m。計算出金屬纖維剖面之 最大剖面高度Η相對於線徑D的比率時，約爲〇.50。此 外，每單位面積之孔的個數約爲2000個/mm2。此外，觀 察到之最大的孔的面積約爲462/im2’具有最大的孔的面 積之1/2以下的面積（亦即約231#m2以下）之孔的個數 相對於孔的全體個數所佔之比率，約爲97%。 例B 3 :開孔率的測定 藉由重量法，以下列方式測定出例B 1中所得之多孔 -22- 201120251 質金屬箔的開孔率。首先，藉由數位測長機（Digimicro MH-ISM，Nikon公司製）測定多孔質金屬箔的膜厚，爲 6.4ym。此時，測定支架係使用MS-5C(Nikon公司製） ，測定件使用Digimicro MH-15M的標準裝備測定件。此 外，測定lOOmmxlOOmm平方的單位重量，爲0.450g。另 —方面，以銀的密度爲10.49g/cm3來計算，求取膜厚6.4 ym、lOOmmxlOOmm平方之無孔質銀箔的理論重量，爲 0.6 72g。使用此等値，以下列方式來計算多孔質金屬箔的 開孔率，而算出3 3 %之値。 (開孔率）=1〇〇-[(樣本的單位重量）/(無孔質銀箔的理論 重量）]X 1 0 0 =1 00-[(0.450)/(0.672)]x 1 00 = 33% 【圖式簡單說明】 第1圖爲本發明之多孔質金屬箔的一例之上方模式圖 〇 第2圖爲構成本發明之多孔質金屬箔的金屬纖維之模 式剖面圖。 第3圖係顯示本發明之多孔質金屬箔的製造步驟的流 程之圖》。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 In the present specification, the present invention relates to a porous metal foil and a method for producing the same. [Prior Art] In recent years, as a portable electronic device such as a mobile phone and a notebook computer, an electric vehicle, and a power storage device for a hybrid electric vehicle, a lithium ion battery and a lithium ion capacitor have attracted attention. The negative electrode current collector of the above-described electrical storage device is a porous metal foil or its use is being investigated. This is made of a porous material, and has a weight-reducing property (the fuel cost of the automobile can be improved). The adhesion of the active material can be enhanced by the anchoring effect of the hole, and the hole can be efficiently used. Advantages such as pre-doping of lithium ions (for example, vertical pre-doping). As a general known method for producing a porous metal foil, (1) the surface of the substrate is shielded into a desired pattern by an insulating coating in advance, and then the electrowinning is applied from the upper side to form a hole. Forming a pattern, (2) imparting a specific surface roughness or surface property to the surface of the substrate in advance, and then applying electrolytic plating from above to control the method of nucleation, (3) by etching or machining A method of perforating a non-porous metal foil - 5, 2011, 20, 251, and (4) a method of forming a three-dimensional mesh structure by a method of electroplating a foamed metal or a non-woven fabric. In particular, with respect to the method of the above (2), since the steps are relatively simple and suitable for mass production, various techniques have been proposed. For example, Patent Document 1 discloses a method of producing a finely-perforated metal foil by subjecting a cathode having a surface roughness Rz of 0.8/zm or less to electrolytic plating. Patent Document 2 discloses that an oxide film is formed on a surface of a cathode body made of titanium or a titanium alloy by anodization, and copper is electrolyzed on a surface of a cathode body to form a porous copper foil, and A method of stripping from a cathode body. Patent Document 3 discloses an open-cell metal foil in which an aluminum alloy carrier is attached, by etching aluminum to form a uniform protrusion, which is used as a core of electrolysis, and gradually causes metal particles. The method of growing and connecting. However, the porous metal foil obtained by such a technique actually has a problem that the strength of the foil is low, so that a sufficiently high opening ratio cannot be obtained. Further, it is difficult to manufacture a long strip, and when the anodic oxidation method is continuously peeled off, the oxide film is destroyed, and there is a problem in the peelability of the porous film and the stability of the open porosity. In particular, in a negative electrode current collector of a power storage device such as a lithium ion battery or a lithium ion capacitor, a higher opening ratio is required as performance is improved. In the present invention, the inventors of the present invention have disclosed the following: Japanese Patent Application Laid-Open No. Hei. No. Hei. No. Hei. No. 2005-251429. This time, it has been found that by performing a metal shovell on a certain peeling layer in which cracks are formed, it is possible to obtain a porous metal foil having preferable characteristics with high productivity and low cost. Accordingly, the object of the present invention is to produce a porous metal foil having better characteristics with high productivity and low cost. That is, according to the present invention, there is provided a porous metal foil formed of a two-dimensional mesh structure composed of metal fibers. Further, according to the present invention, there is provided a porous metal foil product comprising: a conductive substrate; a release layer provided on the conductive substrate; and a porous metal foil provided on the release layer. The peeling layer may be one in which the porous metal foil is peeled off from the peeling layer. Further, according to the present invention, there is provided a method for producing a porous metal foil, comprising: forming a release layer on a conductive substrate; and in this case, cracking occurs in the release layer, and the turtle can be preferentially precipitated The cracked metal is plated on the peeling layer, and a plurality of metal particles are grown along the crack to form a porous metal foil formed of a two-dimensional mesh structure composed of metal fibers. [Embodiment] Porous Metal Foil Fig. 1 is an upper schematic view of an example of a porous metal foil of the present invention 201120251. As shown in Fig. 1, the porous metal foil 1 〇 ' of the present invention is formed of a two-dimensional mesh structure composed of metal fibers 11. The porous metal foil 10 preferably has 3 to 80%, more preferably 5 to 60% Å, more preferably 10 to 55%, and particularly preferably 20 to 55%. Here, the opening ratio P (%) is a ratio of the weight Wp of the porous metal foil to the theoretical weight Wn of the non-porous metal foil having the same composition and size as that of the porous metal foil. Wn, which is defined by P = l〇〇-[( Wp/Wn) xlOO]. The theoretical weight Wn is calculated by measuring the size of the obtained porous metal foil, calculating the volume from the measured size (that is, the volume of the theoretical non-porous metal foil), and preparing the porous metal. The density of the material of the foil is multiplied by the volume obtained thereby. As described above, in the porous metal foil of the present invention, even if the opening ratio is increased, high strength can be exhibited by the numerous metal fibers 11 which are distributed in a two-dimensional mesh shape. Therefore, it is possible to increase the opening ratio to a level that has not been achieved before, without worrying about the strength reduction. For example, the porous metal foil 1 〇 can preferably have a tensile strength measured by a measuring method described later of 10 N/10 mm or more, and more preferably 15 N/I 0 mm or more, thereby being effectively prevented. Breakage of the porous metal foil. In particular, when the carrier is treated in a state of being attached to the porous metal foil, there is no problem even if the tensile strength is lower than the above range. At this time, the opening ratio can be increased to the limit without worrying about the tensile strength. The porous metal foil preferably has a thickness of 3 to 40 #m, more preferably 3 to 30 μm, more preferably 5 to 25/zm, and particularly preferably 1 to 20 private m, preferably 10 to 15/ Zm. When it is within this range, the high opening ratio and the high strength are both good -8 - 201120251. Since the porous metal foil of the present invention is formed of a two-dimensional mesh structure composed of metal fibers, the thickness of the porous metal foil is equivalent to the maximum cross-sectional height of the metal fibers. This thickness is preferably measured by a commercially available film thickness measuring device using a measuring member having a larger pore size than a porous metal foil. The metal fiber π is a fiber made of metal, and the metal to be used can be appropriately determined depending on the application, and is not particularly limited. Preferably, the metal is composed of at least one selected from the group consisting of copper, aluminum, gold, silver, nickel, cobalt, and tin. Here, the term "containing and forming" means that the metal or alloy containing the above-mentioned metal elements is preferable, and it is preferable to contain other metal elements or unavoidable impurities as the remaining part. 50% by weight or more of the metal and the alloy are composed of the above-exemplified metal elements, and typical examples thereof include the above-exemplified metal elements and unavoidable impurities. These definitions are equally applicable to the same performance as described for the metals listed below. Among these metals, the negative electrode current collector applied to a power storage device such as a lithium ion battery or a lithium ion capacitor includes at least one selected from the group consisting of copper, copper alloy, nickel, cobalt, and tin. Especially good for copper. In particular, the two-dimensional mesh structure preferably has an irregular shape resulting from cracks formed on the surface of the substrate. The wire diameter of the metal fiber 11 is preferably 5 to 80 m, more preferably 5 to 50 μm', more preferably 8 to 30 / zm, most preferably 10 to 20; / m. The "wire diameter" is defined as the width (thickness) of the fiber 11 when the porous metal foil is viewed from directly above, and can be measured by a field emission type scanning electron microscope (FE-SEM) or a scanning ion microscope (SIM). . When located in this range, the high opening -9 - 201120251 rate and high intensity balance is good. According to a preferred embodiment of the present invention, as shown in Fig. 1, the metal 11 is a branched fiber, and the branched fibers are irregularly distributed throughout the porous metal foil. The fiber 11 is formed by nucleation along the peeling layer which will be described later, and an infinite number of metal particles are connected to each other to form a metal fiber. It is preferable that the adjacent metal particles are tightly bonded by particle growth. Metal particles of metal fibers may also have incomplete particle shapes. Further, as shown in Fig. 2, the metal particles constituting the metal 11 are typically provided in a hemispherical shape having a spherical portion 11a and a bottom portion, and the bottom lib of all the metal particles is located on the same bottom surface, and all of the metal particles are The spherical portion 11a is based on the same side with the base surface. At this time, along the width D of the bottom surface 1 1 b of the base surface, the maximum cross-sectional height Η of the spherical portion 11 a corresponds to the thickness of the porous gold. The base surface and the bottom portion lib located above it are the planar shape of the peeling layer used in the reverse manufacturing, and are not limited to this shape by other methods. According to the experience of the present inventors, in 1 1 , the average ratio of the maximum profile height Η to the wire diameter D is not limited, and is typically 0.30 to 0.70, especially 0.40 to 0.60, and the type is 0.45 to 0.55, most typically 0.50, this average ratio can be adjusted by changing the plating conditions and the like. Further, according to the present inventors, the average area of the pores of the porous metal foil 10 is not particularly limited to 3 to 5,000! 112, especially typically 3~3 000/^1112, more typical 3~2〇〇〇 y m2. Furthermore, according to the experience of the present inventors, the porous foil 10 has an area of 1/2 or less of the area of the largest pore (the turtle composed of fibers has a fiber lib and a reference position to be a foil-like projection. There is no particular limitation on the ratio of the number of holes of the metal, that is, the average type of the metal, that is, -10-201120251 and about 23 5 0 v m2 or less, relative to the total number of the holes, and is generally 6 More than 〇%, especially typically 70% or more, more typically 80% or more. (Production method) Hereinafter, an example of a method for producing a porous metal foil of the present invention will be described. However, the porous metal foil of the present invention is not limited to this production method, and includes those produced by different production methods. Fig. 3 is a view showing the flow of the manufacturing steps of the porous metal foil of the present invention. In the production method of the present invention, first, the conductive substrate 12 is prepared as a support for producing a porous metal foil. The conductive substrate may be any substrate having conductivity capable of being plated, and any of an inorganic material, an organic material, a laminate, and a material made of a metal may be used, and preferably a metal. . Preferred examples of such a metal include metals such as copper, nickel, cobalt, iron, chromium, tin 'zinc, indium, silver, gold, aluminum, and titanium, and alloys containing at least one of these metal elements. Particularly preferred are copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, and stainless steel. The form of the conductive substrate is not limited, and various substrates such as foils, plates, and rolls can be used. In the case of the drum, the conductive metal plate can be wound around the drum body. The thickness of the conductive metal plate at this time is preferably 1 to 20 mm. The conductive substrate ' is previously supported by the porous metal foil produced in advance or before use to improve the handleability of the porous metal foil. In particular, when a metal foil is used as a conductive substrate, the metal foil as a conductive substrate can be directly reused after the production of the porous metal foil, or -11 - 201120251 is dissolved and foiled. The advantage of recycling is preferred. In this case, when the thickness of the metal foil is 10/m to 1 mm, it is preferable to ensure that the strength of the wrinkles does not occur in the manufacturing process and the subsequent processing and transport steps of the metal foil. Since the shape of the crack of the peeling layer differs depending on the material or the roughness of the conductive substrate, the characteristics such as the opening ratio of the porous metal foil may vary. On the other hand, the shape of the porous metal foil may vary depending on the type of metal plating or the plating conditions. Therefore, it is only necessary to take the consideration of such a situation to obtain a desired porous metal foil. The selection of the conductive substrate, the formation conditions of the release layer, and/or the setting of the shovel conditions may be performed. Then, the peeling layer 13 is formed on the conductive substrate 12, and at this time, the crack 13a is generated on the peeling layer 13. It is preferable that the conductive substrate 12 is previously subjected to an acid cleaning, degreasing or the like before the formation of the peeling layer 13 to clean the surface. The peeling layer 13 is a layer for facilitating the peeling of the porous metal foil 10 formed thereon, so that the crack 13a can be generated, the crack 13a is easily plated, and the crack-free portion 13b is not easily used. A material that is plated in nature. That is, a material which can preferentially precipitate a certain metal on the generated crack 13a by electroplating is used as the peeling layer 13. Further, the release layer may be formed in a plurality of layers. In this case, it may be that only the upper layer is formed with a crack, or not only the upper layer, but also a layer formed below the layer. Further, diamond-like carbon (DLC) or the like may be present on the surface of the release layer. The crack is 13 3 a, preferably controlled by the stress of the peeling layer 13 , or may be formed at the same time as the film formation, but after the -12-201120251 washing and drying step, the machine An undesired product produced in processing or the like is characterized by the use of the crack in the manufacturing method of the present invention. In particular, cracks are regularly formed in a two-dimensional mesh shape to form metal fibers, and a highly open-cell metal foil can be obtained. As for the cracking, it is produced in the general film-forming process. Therefore, the conditions for the production of the film-forming industry can be easily controlled by the composition of the electroplating bath and the conditions of the stripping density. The bath temperature, the stirring condition, and the post-heating peeling layer 13 are preferably composed of at least one selected from the group consisting of chromium and tungsten, or a resin, and are continuously peelable and durable. In view of the fact, it is preferable that the film contains at least one selected from the group consisting of chromium having a high hardness, and it is preferable that the thickness of the chromium, chromium alloy or chromium oxide layer 13 is preferably from the point of the passive state. Lnm~100//m, especially preferably 1~30/zm, and most preferably 2~15/zm. By the thickness, cracks can be generated, and at the same time, the peeling material can be made high in resistance and the porous film formed on the layer can be peeled off. Therefore, the release layer is preferably a material selected from a resistor. The method of forming the peeling layer 13 is not particularly limited to plating, electroless plating, sputtering, or physical vapor deposition. Cracks are generally medium, but instead they are positively branched. Therefore, they are empirically well-chosen in terms of the rate and high-strength porous order that are often worried about their production. For example, it can be separated from the thickness of the layer, current, etc., titanium, group, niobium, and nickel are excised by organic matter (for example, the formation of corrosion and corrosion, titanium, and nickel). The detachment _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ , -13 - 201120251 Various film forming methods such as vapor deposition (CVD), sol-gel method, particle vapor deposition, etc. The release layer 13 is preferably also electrolytically plated from the viewpoint of production efficiency and the like. The peeling layer 13 may be subjected to heat treatment and/or honing as necessary within the scope of the gist of the present invention. That is, the honing may allow the degree of washing the surface, but of course, it may not be excessively performed. The peeling layer 13 thus obtained is preferably washed and dried by water or the like. When performing electrolytic chrome plating, a preferred chrome plating bath is a Sargent bath. And a hard chrome bath, especially a hard chrome bath. Examples of the hard chrome plating bath include Anchor-1127 manufactured by Meltex Co., Ltd., HEEF-25 manufactured by Atotech Co., Ltd., and Mac® manufactured by MacDermi Co., Ltd. 1. The bath composition and plating conditions of these chrome plating baths are as follows, but As long as the desired porous metal foil can be obtained, it can also be deviated from the range shown below. -14 - 201120251 [Table 1] Table 1: Composition of preferred chrome plating bath and plating conditions Basic bath 硬Sold hard chrome bath Sargent Bath Anchor-1127 HEEF-25 Mac · 1 bath composition (g / L) chromic anhydride 250 280-320 200-300 250-300 sulfuric acid 2.5 3.3 ~ 3.9 (ll ~ 1.3wt%) 2.0-4.5 3.5-4.0 Plating Conditions Cathodic Current Density (A/dm2) 20-40 30-60 20-90 10-100 Temperature (.〇45-60 55-60 50-65 55-60 Stabilized chrome bath, typically with a small amount of 3 valence Chromium, the amount is about 2 to 6 g / L. In addition, a catalyst such as an organic sulfonic acid may be added to the hard chromium plating bath. The concentration of chromic anhydride can be managed by Baume degree. Furthermore, due to iron and copper. Impurities such as chloride ions may affect the plating state, so it is necessary to pay attention to the upper limit tube of the amount of impurities dissolved. For the anode used in the chrome ore, it is preferable to use a coating of lead oxide or a Pb-Sn alloy on titanium, and a representative commercial product of the anode is exemplified by the Ti-Pb electrode of SPF (Sn: 5). %) and Exceload LD made by Japan Carlit. Then, the metal which is preferentially precipitated from the crack 13a is plated on the peeling layer 13, and the innumerable metal particles 11 are grown along the crack 13a, thereby forming a porous body formed of a two-dimensional mesh structure composed of metal fibers. Metal box 10. As described above, the release layer 13 is provided with a crack 13a which is easily plated, and a surface portion m which is not cracked by plating. In the case where the crack 13a is easily plated, the portion having the crack 13a is -15-201120251, and the current is more circulated than the crack-free portion 13b. Therefore, the nucleation and growth thereof are preferentially generated in the crack 13a. The metal of the crack 13a may be preferentially deposited, preferably containing at least one selected from the group consisting of copper, aluminum, gold, silver, nickel 'cobalt' and tin, and particularly preferably selected from the group consisting of copper and silver. At least one of the groups formed by Kim and is made of copper. The method for forming the porous metal foil 1 is not particularly limited, and examples thereof include electrolytic plating and electroless plating, and it is preferable to electrolytically deposit metal by cracking 13 3 a. The conditions for electroplating can be carried out in accordance with a generally known method, and are not particularly limited. For example, when copper plating is performed, it is preferably carried out by a copper sulfate bath. When copper plating is performed, the composition and plating conditions of the electroplating bath are copper sulfate pentahydrate concentration: 120~3 50 g/L, sulfuric acid concentration: 50~200 g/L, and cathode current density: l〇~80A/dm2. Bath temperature: 40 to 60 ° C, but is not limited to this. As the plating solution, an additive may be appropriately added to enhance the characteristics of the metal foil. For example, in the case of a copper foil, preferred examples of the additive include a sulfur-containing compound such as a gel, gelatin, chlorine or thiourea, and a synthetic-based additive such as polyethylene glycol. By using these preferred additives, the mechanical properties and surface state of the metal foil can be controlled. The concentration of the additive is not particularly limited, and is generally from 1 to 30,000 ppm. Finally, the porous metal foil is peeled off from the conductive substrate having the release layer to obtain a porous metal foil. After peeling, it can be transferred to another substrate such as a film with an adhesive. However, the stripping step is not necessary, and it can be directly used as a porous metal foil product in a state in which a substrate is attached to the peeling layer, and is peeled off again at the time of use. In this case, not only porous gold-16 - 201120251 The handling property of the foil is improved, and since such a high strength is not required to be supported by the substrate, it is possible to constitute an extremely high opening ratio or an extremely thin film thickness. Application Examples of the porous metal foil of the present invention include a negative electrode current collector of a power storage device such as a lithium ion battery and a lithium ion capacitor, and can be used for fine powder classification or solid-liquid separation treatment. The screen device used, the support for the catalyst, the mesh for the oxygen supply port for the storage container for microorganisms, the dust filter for the clean room, the filter for liquid modification, the electromagnetic wave shield, the magnetic material, and the conductive material Various uses of materials, decorative sheets, and the like. For example, by using a porous metal foil as a conductive material or the like in the inner layer of the printed circuit board, gas derived from a resin or a solvent can be dissipated from the holes, whereby generation of bubbles (expansion) can be suppressed. Further, the use of a porous metal case as a material for electrical conduction or the like in the formation of a circuit can achieve weight reduction due to a decrease in the amount of metal used. EXAMPLES The present invention will be more specifically illustrated by the following examples. Example A 1 : Preparation of porous metal foil A copper foil having a thickness of 3 5 /z m was prepared as a conductive substrate. This copper foil was subjected to chrome plating as a release layer in the following procedure. First, the copper box was immersed in an acid cleaning liquid (manufactured by Murata Co., Ltd. 'pAC_2〇〇) of the printed wiring board adjusted to 1 20 mL/L for 2 minutes under the condition of 4 Å. The copper foil thus washed by this -17-201120251 was immersed in 50 mL/L of sulfuric acid at room temperature for 1 minute to carry out acid activation. The acid-activated copper foil was immersed in a chrome-plated bath of 18 cm/L of Econochrome 300 (manufactured by Meltex) and lg/L of purified concentrated sulfuric acid at a temperature of 45 ° C and a current density of 20 A/dm 2 . Perform chrome plating for 15 minutes. The copper foil on which the chrome plating layer was formed was washed with water and dried. The thickness of the obtained chrome plating layer was measured by XRF (fluorescence X-ray analysis) to be about 2 #m. On the surface of the chrome plating layer, it was confirmed that there were numerous cracks due to plating stress. Copper sulphate is applied to the chrome plating layer that produces the crack. The copper sulfate plating is performed by applying a chrome-plated copper foil to a copper sulfate bath containing 25 Og/L of copper sulfate pentahydrate (copper concentration of about 64 g/L) and sulfuric acid of 80 g/L. Current density: 20 A/dm2, plating time: 150 seconds, anode: DSE (insoluble electrode for oxygen generation), and bath temperature: 40 °C. At this time, since the current is more likely to flow on the cracked portion than the outermost surface of the chrome plating layer, the copper particles grow from the crack as a starting point. As a result, a two-dimensional mesh structure composed of copper fibers can be formed on the chrome plating layer as a porous metal foil. Finally, the porous metal foil was physically peeled off from the chrome plating layer to obtain a separated porous metal foil. Example A2: Observation of Porous Metal Foil The porous metal foil obtained in Example A1 was observed from various angles by a field emission type scanning electron microscope (FE-SEM). First, the surface of the porous metal foil that is not in contact with the peeling layer (hereinafter referred to as the growth surface) is observed from the upper side (inclination angle) and the obliquely upward direction (inclination angle of 45 degrees), respectively, -18-201120251 4 and the image shown in Figure 5. In addition, the surface of the porous metal foil which is in contact with the peeling layer (hereinafter referred to as a peeling surface) is observed from the upper side (inclination angle) and the upper side (inclination angle of 45 degrees), respectively, and obtained as follows. The images shown in Figures 6 and 7. As can be seen from the above figures, the bead-like irregularities caused by the spherical portions of the metal particles can be observed on the growth surface, whereas the peeling surface can be observed as a plane originating from the bottom of the metal particles and along the cracks. The centerline formed. Further, after the cross section of the metal fiber of the porous metal foil was processed by a bundled ion beam processing apparatus (FIB), an image as shown in Fig. 8 was obtained by observation using a scanning ion microscope (SIM). As shown in the figure, it can be observed that the cross-sectional structure of the metal fiber is radiated as a starting point from the crack, and the cross-sectional shape of the metal fiber is a half-moon shape including a spherical portion and a planar bottom surface. When the wire diameter (thickness) of the metal fiber is calculated from the ruler shown in these figures, it is 30 μm. Calculate the ratio of the maximum profile height Η of the metal fiber profile to the wire diameter D, which is about 0.5 0. Further, the number of holes per unit area is about 300/mm2. In addition, the largest pore area observed is about 4700 μm 2 , and the number of pores having an area of 1/2 or less of the largest pore area (that is, about 2 3 5 0 y m 2 or less) is relative to the pore size. The ratio of the total number is about 90%. Example A3: Measurement of open cell ratio The open cell ratio of the porous metal foil obtained in Example A1 was measured by the gravimetric method in the following manner. First, the film thickness of the porous metal foil was measured by a digital length measuring machine (Digimicro ΜΗ-1 5M, manufactured by Nikon Corporation) to be -19-201120251 14.7; zm. In this case, MS-5C (manufactured by Nikon Co., Ltd.) was used for the measurement, and the standard equipment was used for the measurement piece using Digimicr ο Μ Η -1 5 ° ° In addition, * the unit weight of 100 mm x 100 mm square was measured as 〇.94 g ° On the other hand, the density of copper was 8.92 g/cm 3 , and the theoretical weight ' of the non-porous copper foil having a film thickness of 14, 7 vm and 100 mm x 100 mm square was 1.31 g. Using these enthalpy, the opening ratio of the porous metal foil was calculated in the following manner, and 28% of the enthalpy was calculated. (opening ratio) = 100-[(unit weight of sample) / (theoretical weight of non-porous copper foil)] xl 〇〇 = 100-[(0.94) / (1.31)] xl00 = 28% Example A4: Pull The tensile strength of the porous metal foil obtained in Example A1 was measured in the following manner by the method according to JIS C6511. First, a test piece of 10 mm x 10 mm was cut out from the porous metal crucible. As shown in Fig. 9, the both ends of the test piece 20 were sandwiched between the upper and lower fixing jigs 21 and 21 of a tensile strength measuring machine (Autograph, manufactured by Shimadzu Corporation) at intervals of 50 mm and fixed. Thereafter, the film was stretched at a stretching speed of 50 mm/min, thereby measuring the tensile strength. At this time, a 1 kN force measuring device was used in the tensile strength measuring machine. As a result, the tensile strength was 15 N/10 mm wide. Further, the elongation of the test piece at this time was 0.8%. From this result, it is considered that the porous metal foil of the present invention has strength which can withstand the practicality of -20-201120251. Example B1: Preparation of Porous Metal Foil A stainless steel plate composed of SUS304 was prepared as a conductive substrate. The stainless steel foil was subjected to 2 cm of chrome plating as a release layer in the following procedure. First, the stainless steel plate was immersed in an acid cleaning liquid (manufactured by Murata Co., Ltd., PAC-2 00) of the printed wiring board adjusted to l2 〇 mL/L for 2 minutes at 40 °C. The stainless steel plate thus washed was immersed in 50 mL/L of sulfuric acid at room temperature for 1 minute to carry out acid activation. The acid-activated stainless steel plate was immersed in a commercially available hard chrome plating bath (HEEF-25, manufactured by Atotech Co., Ltd.) at a cathode current density: 20 A/dm2, electrolysis time: 400 seconds, bath temperature: 45 ° C, coulomb Amount: 8000 C / dm 2 , electrode area: 1.2 dm 2 , interelectrode distance: 90 mm, chrome plating. The stainless steel plate having the ore chromium layer is washed and dried. The thickness of the obtained chrome plating layer was measured by XRF (fluorescence X-ray analysis) to be about 2 // m. On the surface of the chrome plating layer, it was confirmed that there were numerous cracks due to plating stress. Silver plating is applied to the chrome layer that produces the crack. This silver plating is applied to a chrome-plated stainless steel plate and immersed in a commercially available mineral silver bath (Selenabright C, in which potassium cyanide 25 g/L, silver cyanide (Ag is 50 g/L), and phosphate are dissolved. It is produced by Japan High Purity Chemical Co., Ltd. under conditions of cathode current density: l.〇A/dm2, electrolysis time: 469 seconds, and bath temperature: 40 °C. At this time, since the current flows more easily on the cracked portion than the outermost surface of the chrome plating layer, the silver particles are formed to have a length of S--21 - 201120251 from the crack. As a result, a two-dimensional mesh structure composed of silver fibers can be formed as a porous metal foil on the chrome plating layer. Finally, the porous metal foil was physically peeled off from the chrome plating layer to obtain a separated porous metal foil. Example B2: Observation of Porous Metal Foil The porous metal foil obtained in Example B1 was observed from various angles by a field emission type scanning electron microscope (FE-SEM). First, the surface of the porous metal foil which is not in contact with the peeling layer (hereinafter referred to as a growth surface) is observed from the upper side (inclination angle), and an image as shown in Fig. 10 is obtained. Further, the porous metal foil was turned over, and the surface of the porous metal foil which was in contact with the peeling layer (hereinafter referred to as a peeling surface) was observed from directly above (inclination angle of 0 degree) to obtain an image as shown in Fig. 11. As can be seen from the above figures, the bead-like irregularities caused by the spherical portions of the metal particles can be observed on the growth surface, whereas the peeling surface can be observed as a plane originating from the bottom of the metal particles and along the cracks. The centerline formed. When the wire diameter (thickness) of the metal fiber is calculated from the ruler shown in these figures, '1 μm. When the ratio of the maximum profile height Η of the metal fiber profile to the wire diameter D is calculated, it is about 〇.50. Further, the number of holes per unit area is about 2,000/mm2. Further, the area of the largest hole observed was about 462/im2', and the number of holes having an area of 1/2 or less of the largest hole area (that is, about 231 #m2 or less) was relative to the total number of holes. The ratio is about 97%. Example B 3: Measurement of open cell ratio The open cell ratio of the porous -22-201120251 metal foil obtained in Example B1 was determined by the gravimetric method in the following manner. First, the film thickness of the porous metal foil was measured by a digital length measuring machine (Digimicro MH-ISM, manufactured by Nikon Corporation) to be 6.4 μm. At this time, MS-5C (manufactured by Nikon Co., Ltd.) was used for the measurement scaffold, and a standard equipment measuring instrument of Digimicro MH-15M was used for the measurement instrument. Further, the unit weight of the square of 100 mm x 100 mm was measured and found to be 0.450 g. On the other hand, the theoretical weight of the non-porous silver foil having a film thickness of 6.4 ym and 100 mm x 100 mm square was calculated by calculating the density of silver to be 10.49 g/cm3, which was 0.672 g. Using these enthalpies, the porosity of the porous metal foil was calculated in the following manner, and 3% of the enthalpy was calculated. (opening ratio) = 1 〇〇 - [(unit weight of sample) / (theoretical weight of non-porous silver foil)] X 1 0 0 =1 00-[(0.450) / (0.672)] x 1 00 = 33 BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic top view showing an example of a porous metal foil of the present invention. Fig. 2 is a schematic cross-sectional view showing a metal fiber constituting the porous metal foil of the present invention. Fig. 3 is a view showing the flow of the manufacturing steps of the porous metal foil of the present invention"
第4圖係在例A2中，從正上方（傾斜角〇度）觀察 本發明之多孔質金屬箔之未與剝離層接觸的面之FE-SEM -23- 201120251 圖像。 第5圖係在例A2中，從斜上方（傾斜角45度）觀 察本發明之多孔質金屬箔之未與剝離層接觸的面之FE-SEM圖像》 第6圖係在例A2中，從正上方（傾斜角0度）觀察 本發明之多孔質金屬箔之與剝離層接觸的面之FE-SEM圖 像。Fig. 4 is an image of FE-SEM-23-201120251 of the surface of the porous metal foil of the present invention which was not in contact with the peeling layer was observed from the upper side (inclination angle) in Example A2. Fig. 5 is a view showing an FE-SEM image of a surface of the porous metal foil of the present invention which is not in contact with the peeling layer from the obliquely upper side (inclination angle of 45 degrees) in the example A2. Fig. 6 is in the example A2. The FE-SEM image of the surface of the porous metal foil of the present invention in contact with the peeling layer was observed from directly above (inclination angle of 0 degree).
第7圖係在例A2中，從斜上方（傾斜角45度）觀 察本發明之多孔質金屬箔之與剝離層接觸的面之FE-SEM 圖像。 第8圖係以表示出將構成在例A2中所得之本發明之 多孔質金屬箔的金屬纖維垂直地切斷之切斷面的傾斜角 60度，來進行觀察之SIM圖像。 第9圖係顯示在例A4中所進行之拉伸強度試驗中之 金屬箔樣本對固定夾具的固定之模式圖。 第10圖係在例B2中，從正上方（傾斜角0度）觀察 本發明之多孔質金屬箔之未與剝離層接觸的面之FE-SEM 圖像。 第1 1圖係在例B 2中，從正上方（傾斜角0度）觀察 本發明之多孔質金屬箔之與剝離層接觸的面之FE-SEM圖 像。 【主要元件符號說明】 1 〇 :多孔質金屬箔 -24- 201120251 1 1 :金屬纖維 1 1 a :球狀部 1 lb :底部 1 2 :導電性基材 1 3 :剝離層 1 3a :龜裂 13b :無龜裂部分 2 0 :試驗片 21 :固定夾具 D :線徑 Η :最大剖面高度 -25-Fig. 7 is a view showing an FE-SEM image of the surface of the porous metal foil of the present invention which is in contact with the peeling layer from the obliquely upper side (inclination angle of 45 degrees) in Example A2. Fig. 8 is a view showing a SIM image in which the angle of inclination of the cut surface of the metal fiber of the porous metal foil of the present invention obtained in Example A2 was cut perpendicularly by 60 degrees. Fig. 9 is a schematic view showing the fixing of the metal foil sample to the fixing jig in the tensile strength test conducted in Example A4. Fig. 10 is an FE-SEM image of the surface of the porous metal foil of the present invention which was not in contact with the peeling layer, as seen from the upper side (inclination angle of 0 degree) in Example B2. In the case of Example B2, the FE-SEM image of the surface of the porous metal foil of the present invention which was in contact with the peeling layer was observed from the upper side (inclination angle of 0 degree). [Explanation of main component symbols] 1 〇: porous metal foil-24- 201120251 1 1 : metal fiber 1 1 a : spherical portion 1 lb : bottom 1 2 : conductive substrate 1 3 : peeling layer 1 3a : crack 13b : No cracking part 2 0 : Test piece 21 : Fixing jig D : Wire diameter Η : Maximum section height -25 -